Anti gas-lock construction for turbine pump



P 7, 1965 E. w. NORQUIST 3,204,562

ANTI GAS-LOCK CONSTRUCTION FOR TURBINE PUMP Filed Sept. 50, 1963 IN VEN TOR.

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M a w [2444 0 (d. Mwau/Jr \iwwmwm 3,204,562 ANTI GAS-LOCK CONSTRUCTION FOR TURBINE PUMP Erland W. Norquist, Berkeley, Calif., assiguor to Berkeley Pump Company, Berkeley, Calif., a corporation of California Filed Sept. 30, 1963, Ser. No. 312,729 4 Claims. (Cl. 103-102) This invention relates to turbine pumps and, more particularly, to pumps constructed with the purpose of eliminating gas-locks, a phenomenon which occurs when entrained gases are centrifuged out of a liquid that is being pumped.

It is commonly known that entrained gas bubbles tend to accumulate along the impeller shaft of a turbine pump as the bubbles are centrifuged inwardly. The accumulation of gas may become such that the amount of liquid acted upon by the impeller blades is insufficient to keep the pump primed, and at this point the pump is said to have formed a gas-lock.

The problem of gas-locks is often experienced by persons who use vertical turbine pumps for-raising fluids from a well bore formed in underground gas-bearing strata. In pumping fluids from certain of these well bores there may be such a rapid build-up of gases within the pump that it is impossible to operate the pump for any prolonged or worthwhile period of time. Under such circumstances, the well may have to be abandoned. However, it is sometimes possible, by adding a tail pipe to the lower end of the turbine pump, to extend its intake end to a level below existing gas-bearing strata, thereby avoiding liquids that contain too much gas. Alternatively, it is also common practice to merely lower the pump further in the well, increasing the pumps submergence and placing its intake below gas-bearing strata. Since this practice also increases the hydrostatic pressure at the pumps intake, the size of entrained gas bubbles is apt to be smaller, thereby decreasing the rate of gas accumulation and the frequency of gas-locks.

As indicated, various devices are now known and used to avoid a gas-lock, but provided certain conditions are found. Under some conditions of operation those devices are of little or no help, or are used with moderate or fair success. In any event, the additional cost and expense of relocating the pumps intake or adding to the length of the pumps housing, must be considered a disadvantage. Thus, it is one primary object of this invention to provide a turbine pump which will operate under adverse conditions where conventional pumps will form a gas-lock and without requiring expensive modifications.

In brief, this invention involves a turbine pump having a fluid passageway for recirculating a small portion of pumped fluid and discharging the fluid back into the flowstream at a point near the axis of impeller rotation and adjacent the leading edges of impeller blades. The small amount of recirculated fluid mixes with any gas that tends to collect along the impeller shaft, forcing the gas bubbles back into the flowstream so that it must pass on through the pump.

In addition, it is contemplated that a passageway of this type may be provided by a tubular impeller shaft having multiple pumping stages; that the inlet opening of said passageway should be smaller than outlet openings to prevent clogging of the recirculating passageway; that the impeller should be preferably of a semi-open type to aid in providing a mixing action; that flow straightening vanes are best employed to a point near the leading blade edges of an impeller and adjacent the discharge opening of the recirculating passageway; and that the recirculating passage for multi-stage pumps (having at least three impellers) should have its inlet opening upstream of the last impeller to avoid recirculating too much sand.

In the drawings forming a part of this application, FIGS. 1 and 2 are longitudinal sections of the upper and lower adjacent portions, respectively, for a vertical turbine, multistage pump constructed in a preferred manner as contemplated by the invention.

Referring to the drawings, there is illustrated a vertical turbine pump of a multi-stage type having a r housing comprising three vertically stacked impeller bowls 11, 12, 13, an inlet sleeve 14, and an outlet sleeve 15. Standard bolt connections 16 secure each of the bowls and sleeves into a unitary assemblage. Impellers 17a, 17b and are respectively housed within the impeller bowls, each impeller having blades 18 with leading edges 19 andbeingsupported upona common drive shaft 20.

Impeller bowls 11, 12 and 13 are essentially the same shape, and each bowl has an internal bearing support 21 mounted from a pair of vanes 22 and 23. Similarly, a

lower terminal bearing 24 is mounted within sleeve 14 lower end by a plug 32 and at its upper end by a plug 33;

and lateral openings 34, 35 and 36 are provided in shaft 20 intermediate plugs 32 and 33. Openings 34, it will be noted, are located between impellers 17b and 170, while openings 35 and 36 are located above and below, respectively, the lowermost impeller 17a. Moreover, each of the openings is located at a point adjacent one of the leading blade surfaces of the impellers, the areas in which gases tend to collect as they are centrifugally separated from liquids.

As with other types of multi-stage turbines, each impeller adds a measure of fluid pressure force, so that the downstream pressure immediately in back of a given impeller is greater than the fluid pressure upstream of that impeller. It will be evident, therefore, that the pressure at openings 34 will be greater than the fluid pressure in the pumps flow stream near openings 35 and 36, which openings are relatively upstream from openings 34. As a consequence, a small part of the fluid passing through ,the pump will be recycled through the passageway 30, said fluid entering openings 34 and being expelled out either opening 35 or 36. As fluid flows out through openings 35 and 36 it will be mixed with any gas that might have collected in this region due to the pumps impelling centrifugal action, and the resulting liquid-gas mixture will pass on through the impeller to the next pumping stage.

It is contemplated that openings 35 and 36 should be of greater size or dimension than inlet openings 34. With such a construction any solid particles, such as sand, which may enter passageway 30 can escape through the outlet openings 35 and 36, thereby preventing a clogging of either the passageway or the outlet openings.

While the present invention may be applied to turbine pumps having either semi-open impellers or closed impellers, the former type of impellers are preferred. A certain amount of water slippage between vanes and stationary impeller bowls is desirable since it produces a mixing effect that helps retain the gases in the liquid as they are advanced from one stage to another.

Referring to FIG. 2, vanes 25 and 26 extend from an Patented Sept. 7, 1965 3 interior wall of housingsleeve 14 into the -area adjacent to the leading edges 19 of impeller 17a. This construction has been found useful since it minimizes any prerotation of the fluid which enters the impeller, thereby eliminating or reducing an early centrifugal separation of gases from the liquid.

It is to be understood that pumps are-staged according. to pumping requirements, andalthough three impeller stages are illustrated the invention canalso be applied to any type of staging including a single stage'uniti How ever, if turbine possessed only the one stage, as might be provided by impeller. 17a alone, then opening 35 would become an inlet. port for recirculating fluid from the discharge side of the impeller backto the area in front of its impeller. blades 18.

It is to be noted that no openings are provided intopassageway 30 at a level above or on the downstream side of impeller 17b. It has been found that there is an increased tendency to pick up sandor other grittymaterials if such an opening is employed-at thatpoint or location in a multi-stage pump.

' Although a preferred embodiment of the invention has been shown and described, it is to be understoodthat various changes may be made'without departing from the spirit of the invention or the scope'of the attached'claims, and each of such changes is contemplated:

What I claim and desire to secure by Letters-Patent is: 1. A multi-stage turbine pump comprising a housing including at least three impeller bowls, an impeller disposed Within each of said three impeller bowls, meansfor driving each ofsaid impellers, anda fluid passageway extending between points on the upstream and down stream sidesof the first two impellers for conducting fluid from an inlet opening at a point downstream of'said second impeller to outlet openings of lower pressure at relatively upstream points adjacent one ofthe leading blade surfaces of said first two impellers, respectively, each outlet opening being located near the axis ofimpeller rotation.

2. A multi-s'tage' vertical turbine pumpcomprising a housing including at least three vertically aligned impeller bowls, a tubular impeller drive shaft supported for rotation within said impeller bowls, an impeller disposed within each of said three impeller bowls and coaxially mounted to said tubular drive shaft, said drive shaft defining a fluid passageway extending between points on opposite sides of the lowermost two impellers, respectively, for conducting fiuid from an inlet opening at a point above both of said two impellers to outlet openings .oflower pressure, each outlet opening being located at points adjacent one of the leading blade surfaces of said lowermost two impellers and including points on both sides, respectively, of the lowermost impeller.

3. The multi-stage vertical turbine pump of claim 2 wherein each of said outlet openings is of greater size than any of said inlet openings.

4'. The multistage vertical turbine pump of claim 2 wherein said housing includes a pair of flow straightening vanes extending frornran interior wall into proximate relation to the leadingblade edge and to the outlet opening adjacent the leading blade. surfaces of said lowermost impeller.

References Cited by the Examiner UNITED STATES PATENTS 2,034.790 3/ 36' Arutunoff. 2,23 6,953 4/41 Schott 103l 02 2,311,963 2/43 Pyle 103- 5 2,331,310 10/43 Damonte l()3l13 FOREIGN PATENTS 475,711 5/29- Germany. 308,442. 3729 Great Britain. 619,722. 3/49 Great Britain. 335,586 2/36 Italy.

DONLEY J. STOCKING, Primary Examiner.

HENRY F. RADUAZO, KARL I. ALBRECHT,

Examiners. 

1. A MULTI-STAGE TURBINE PUMP COMPRISING A HOUSING INCLUDING AT LEAST THREE IMPELLER BOWLS, AN IMPELLER DISPOSED WITHIN EACH OF SAID THREE IMPELLER BOWLS, MEANS FOR DRIVING EACH OF SAID IMPELLERS, AND A FLUID PASSAGEWAY EXTENDING BETWEEN POINTS ON THE UPSTREAM AND DOWNSTREAM SIDES OF THE FIRST TWO IMPELLERS FOR CONDUCTING FLUID FROM AN INLET OPENING AT A POINT DOWNSTREAM OF SAID SECOND IMPELLER TO OUTLET OPENINGS OF LOWER PRESSURE AT RELATIVELY UPSTREAM POINTS ADJACENT ONE OF THE LEADING BLADE SURFACES OF SAID FIRST TWO IMPELLERS, RESPECTIVELY, EACH OUTLET OPENING BEING LOCATED NEAR THE AXIS OF IMPELLER ROTATION. 